When a vehicle's OBC draws the maximum current of the EVSE under faulty AC outlet circuit conditions it may cause the circuit breaker to trip, or cause other undesirable conditions.
EV charging is the primary function of the OBC which takes AC input from a source (e.g., home, building, generator, or other source of power) and converts it to DC output to charge a high voltage battery (HV battery) on board the EV for powering the electric motor. To do this safely in current applications the OBC receives a maximum current limit signal from an Electric Vehicle Supply Equipment (EVSE) as defined, for example, in SAE J1772. SAE J1772 is a standard for electrical connectors for EVs followed in North America, and describes the standards for the physical plug layout of the electrical connectors, electrical characteristics including performance requirements (e.g., charging currents and maximum current limits during a charging operation), and communication protocols transferred through the electrical connectors. In certain scenarios where the source is a DC source, the OBC may work together with the EVSE to achieve charging of the HV battery.
Although the OBC may be supplied with a maximum current limit from the EVSE, preventing the OBC from reaching the maximum current limit may still be desired.